1. Field of the Invention
The present invention relates generally to computer security, and more particularly but not exclusively to methods and apparatus for checking for malicious changes to web pages.
2. Description of the Background Art
Computer viruses, worms, Trojans, rootkits, and spyware are examples of malicious codes that have plagued computer systems throughout the world. Although there are technical differences between each type of malicious code, malicious codes are also collectively referred to as “viruses.” Antivirus products for protecting computers against known viruses are commercially available. Experienced computer users have installed some form of antivirus in their computers and have learned not to open suspicious files to avoid virus infection.
The Internet provides an effective medium not only for sharing information but also, unfortunately, for spreading viruses and perpetrating online fraud. For example, distribution of viruses no longer requires a user to open a file or receive an infected email. A computer may be infected or compromised simply by accessing websites, even those that are known to be legitimate. A legitimate website may be attacked by a cyber criminal (e.g., hacker) and make malicious modifications to its web pages. The malicious modifications may redirect the user to a malicious website to perpetrate a fraudulent scheme (e.g., phishing) or to infect the user's computer with a virus.